Design a Parking Lot

Requirements

• The lot has multiple levels, each with a fixed number of spots of different sizes (motorcycle, compact, large).
• A vehicle can only park in a spot that fits its size (a motorcycle can use any spot; a large vehicle needs a large spot).
• Support issuing a ticket on entry and calculating a fee on exit based on duration.
• Track which spots are free in real time so a display can show availability per level.

Key classes to identify before you look at the reference

Think through: what represents a parking spot? A vehicle? What decides which spot a vehicle gets? Where does the fee calculation live, and why should it be a separate class from the ticket itself?

Which patterns apply

Consider: how would you support adding a new vehicle size (e.g. "oversized") without editing every place that currently checks if vehicle.size == ...? How would you support multiple fee-calculation schemes (flat rate vs. per-hour vs. weekend pricing) that can be swapped independently?